Abstract and registration

[Bernard Zygelman <bernard@physics.unlv.edu>]

Registration form
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Last name:Zygelman
First name:Bernard
Middle name/initial:
Affiliation:Dept. of Physics, UNLV
Street Address: 
City:Las Vegas
State:NV
Postal Code:89154
Country:USA
Tel:702-895-1321
Fax:702-895-0804
E mail:bernard@physics.unlv.edu
Citizenship*:USA
Abstract title  Hydrogen Atom Collisions and Tomography of the Dark Age 
Universe
Special requirements:
*Non-US citizens should contact Cara Loomis if travel reimbursement for the 
Workshop is required.


Registration form
-------------------------------------------------------------------------------
----------------------
Last name:Zygelman
First name:Bernard
Middle name/initial:
Affiliation:Dept. of Physics, UNLV
Street Address: 
City:Las Vegas
State:NV
Postal Code:89154
Country:USA
Tel:702-895-1321
Fax:702-895-0804
E mail:bernard@physics.unlv.edu
Citizenship*:USA
Abstract title  Hydrogen Atom Collisions and Tomography of the Dark Age 
Universe
Special requirements:
*Non-US citizens should contact Cara Loomis if travel reimbursement for the 
Workshop is required.

Please find my abstract below. 



% Sample abstract for submission to NASA LAW 2006.
% See page 181-183 of Leslie Lamport's LaTeX book (second edition)
% for more info.
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\documentclass{article}
\begin{document}
\title{Hydrogen Atom Collisions and Tomography of the Dark Age Universe}
\author{B. Zygelman, Dept. of Physics, UNLV}
\maketitle
\begin{abstract}
We present  collision data for
hyperfine level changing transitions in atomic hydrogen. Recent proposals[1]
have suggested that observation of the red-shifted
hydrogen 21 cm line could provide unprecedented information on matter density 
fluctuations
in the early universe. If the spin temperature of atomic hydrogen falls below 
the temperature of the background radiation field (CBR), regions of dense 
primordial hydrogen absorb radiation at 21 cm. The resulting features could be 
detected with proposed next generation radio telescopes.
However, the decoupling of matter and radiation temperature depends crucially 
on the collision properties of the hydrogen system[2]. Our calculated 
collision data, which significantly improves upon previous results, confirms 
that for  $ 30 < z <200$, 21 cm absorption is efficient and
enables proposed tomography of the dark age universe. We also discuss the role 
of spin-exchange vs. long range dipolar spin changing transitions in 
determining the level populations of atomic
 hydrogen in the dark age epoch.
\vskip 30 pt \noindent
[1] Loeb \& Zaldarriaga Phys. Rev. lett. 92, 211301 (2004). \vskip 3 pt 
\noindent
[2] B. Zygelman, ApJ 622 1356 (2005).  
\end{abstract}


\end{document}